how does lllt work

What is lllt ?

how does lllt work

how does lllt work

how does lllt work

What is LLLT?-LLLT (Low Level Laser Therapy) is the application of red and near infra-red light over injuries or lesions to improve wound and soft tissue healing, reduce inflammation and give relief for both acute and chronic pain. First developed in 1967, it is now commonly referred to as LLLT.

LLLT is used to: increase the speed, quality and tensile strength of tissue repair; resolve inflammation and relieve pain (analgesia).

The red and near infrared light (600nm-1000nm) commonly used in LLLT can be produced by laser or high intensity LEDs. The intensity of LLLT lasers and LED’s is not high like a surgical laser. There is no heating effect.

The effects of LLLT are photochemical (like photosynthesis in plants). When the correct intensity and treatment times are used, red and near infrared light reduces oxidative stress and increases ATP. This improves cell metabolism and reduce inflammation. These effects can be enhanced with pulses however when analgesia is required there is a second mechanism which works best when a strong continuous beam is applied.

Download ‘LLLT dose review (PDF)’
This paper from Harvard Medical School reviews the LLLT mechanisms and the biphasic dose response. It summarises the molecular and cellular mechanisms of LLLT, gives a scientific explanation for the biphasic dose response (why a low dose has a stimulatory effect and why a high dose inhibits). Low power densities tend to get better healing and anti-inflammatory effects where higher power densities are more likely to inhibit (which may be useful if you just want an analgesic effect). I have to disclose an interest in this paper because I am a co-author. James Carroll CEO THOR Photomedicine.

What is History of LLLT?-In 1903, Dr. Nils Finsen was awarded a Nobel Prize for his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation . In 1960, Professor Maiman TH built the first working red ruby laser , but it was not until 1967 when Mester E et al. was able to demonstrate the phenomenon of “laser bio stimulation” . In 1999, Whelan H et al. presented his work on the medical applications of light emitting diodes (LED) for use on the NASA space station . Subsequently over 400 Phase III randomized, double-blind, placebo-controlled trials have been published, with over 4000 laboratory studies of LLLT. (Pubmed.gov)

A laser is a device that generates light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. There are four main classes of lasers as defined by the International Engineering Consortium (IEC standard 60825.) These classes indicate potential danger the radiation is to the eye.

LLLT is the application of light (usually a low powered laser or LED typically power range of (10mW–500mW). Light with a wavelength in the red to near infrared region of the spectrum (660nm–905nm), is generally employed because these wavelengths have the ability to penetrate skin, and soft/hard tissues (Figure 2) and are proven in clinical trials to have a good effect on pain, inflammation and tissue repair. The power density (irradiance) is usually between 5W/cm2 and is applied to an injury or to a painful site for 30–60 seconds a few times a week for several weeks. The result is a reduction of inflammation, pain relief and accelerated tissue regeneration. In most cases the lasers/LEDs used for LLLT emit a divergent beam (not focused or collimated) because collimation is lost in tissue, but as a consequence ocular risks are also diminished over distance.

how does lllt work?

How Does LLLT work?-The effects of LLLT are photochemical(cold), not thermal. During treatment of the tissue with the 635nm laser, an interaction between cells and photons takes place: a photochemical reaction. Photons from the laser affect the tissue at the cellular level. The cold laser enters the tissue, alters cell membrane permeability, and at the cellular level is absorbed in the mitochondria. The mitochondria are the “powerhouse” of cells and make ATP which is needed for the life enhancement process of every cell which facilitates:The effects of LLLT are photochemical(cold), not thermal. During treatment of the tissue with the 635nm laser, an interaction between cells and photons takes place: a photochemical reaction. Photons from the laser affect the tissue at the cellular level. The cold laser enters the tissue, alters cell membrane permeability, and at the cellular level is absorbed in the mitochondria. The mitochondria are the “powerhouse” of cells and make ATP which is needed for the life enhancement process of every cell which facilitates:

– rapid cell growth. The laser accelerates cellular reproduction and growth.
– faster wound healing. The laser stimulates fibroblast development in the damaged tissue. The reduction in recovery time is an important consideration
– increased metabolic activity. Helps the body increase output of specific enzymes, greater oxygen to blood cells and more effective immune reponse are induced by laser
– reduced fibrous tissue formation. The laser reduces formation of scar tissue following tissue damage from cuts, scratches, burns, or following surgery
– anti-inflammatory action. The laser reduces swelling caused by bruising or inflammtion of joints to give improved joint mobility.
– increased vascular activity. The laser stimulates lymph and blood circulation, to allow the affected tissue to have the best possible circulation
– stimulate nerve function. Slow recovery of nerve function in damaged tissue can result in “dead” limb or numb areas. Laser will speed the process of nerve cell reconnection to bring the numb area back to life. Laser also increases the amplitude of action potentials to optimize muscle action.

How LLLT to the treatment of pain?

Acute orthopedic conditions such as sprains , strains, post-surgical pain, a whiplash injury , muscular back pain, cervical or lumbar radiculopathy, tendinitis and chronic conditions such as osteoarthritis , rheumatoid arthritis, frozen shoulder, neck and back pain, epicondylitis, carpal tunnel syndrome, tendinopathy, fibromyalgia, plantar fasciitis, post tibial fracture surgery and chronic regional pain syndrome are amenable to LLLT. Dental conditions producing pain such as orthodontic procedures, dentine hypersensitivity, and third molar surgery respond well to treatment with LLLT. Neuropathic pain conditions can also be treated such as post herpetic neuralgia, trigeminal neuralgia , and diabetic neuropathy. Due to the wide spectrum of conditions one would surmise that multiple mechanisms can operate to achieve pain relief.

The peripheral nerve endings of nociceptors, consisting of the thinly myelinated A∂ and unmyelinated, slow-conducting C fibers, lie within the epidermis. This complex network transduces noxious stimuli into action potentials. Moreover these nerve endings are very superficial in nature and thus are easily within the penetration depths of the wavelengths used in LLLT. The cell bodies of neurons lie within the dorsal nerve root ganglion, but the elongated cytoplasm (axons) of the neurons extends from the cell body to the bare nerve endings in the surface of the skin. The direct effect of LLLT are initially at the level of the epidermal neural network, but the effects move to nerves in subcutaneous tissues, sympathetic ganglia, and the neuromuscular junctions within muscles and nerve trunks.

LLLT applied with a sufficient level of intensity causes an inhibition of action potentials where there is an approximately 30% neural blockade within 10 to 20 minutes of application, and which is reversed within about 24 hours . The laser application to a peripheral nerve does have a cascade effect whereby there is suppressed synaptic activity in second order neurons so that cortical areas of the pain matrix would not be activated.

Adenosine triphosphate (ATP) is the source of energy for all cells, and in neurons this ATP is synthesized by mitochondria while they are located in the dorsal root ganglion. These mitochondria are then transported along the cytoskeleton of the nerve by a monorail system of molecular motors. LLLT acts like an anesthetic agent, in that both LLLT and anesthetics have been shown to temporally disrupt the cytoskeleton for a matter of hours as evidenced by formation of reversible varicosities or beading along the axons, which in turn cause mitochondria to “pile up” where the cytoskeleton is disrupted. The exact mechanism for this effect is unknown but it is not a thermal action. It has been shown that LLLT at the correct dose decreases mitochondrial membrane potential (MMP) in DRG neurons and that ATP production is then reduced so perhaps the lack of ATP could be cause of this neural blockade. The most immediate effect of nociceptor blockade is pain relief which occurs in a few minutes and has been shown by the timed onset of a conduction blockade in somatosensory-evoked potentials (SSEPs). This inhibition of peripheral sensitization not only lowers the activation threshold of nerves but also decreases the release of pro inflammatory neuropeptides (i.e. substance P and CGRP). In persistent pain disorders this reduction of tonic input to activated nociceptors and their synaptic connections, leads to a long-term down-regulation of second-order neurons. The modulation of neurotransmitters is a further possible mechanism of pain relief, as serotonin and endorphin levels have been shown to increase in animal models and following laser treatment of myofascial pain in patients [81]. Thus LLLT can have short, medium and long term effects. Fast acting pain relief occurs within minutes of application, which is a result of a neural blockade of the peripheral and sympathetic nerves and the release of neuromuscular contractions leading to in a reduction of muscle spasms.

In the medium term there is a decrease of local edema and a reduction of inflammation within hours to days. The action of LLLT in reducing swelling and inflammation has been well established in animal models as well as in clinical trials. The numbers of inflammatory cells has been shown to be reduced in joints injected with protease, in collagen-induced rheumatoid arthritis, and in acute pulmonary inflammation . The expression levels of pro-inflammatory cytokines have been shown to be reduced by LLLT in burn wounds, in muscle cryo lesions and in delayed type hypersensitivity. The long term effects of LLLT occur within a week or two and can last for months and sometimes years as a result of improved tissue healing.